1. Field of the Invention
The present invention is directed to an acousto-optical data input transducer and a method for using the transducer in an arrangement for holographically recording data on the storage medium in the form of block-organized holographic data. The input transducer consists of an acousto-optical light deflector operated by electrical signals and a laser whose light beam is spatially modulated into a plurality of object beams by an acousto-optical light deflector and directed to a storage medium for recording.
2. Prior Art
Acousto-optical data input transducers for holographic data recording are disclosed for example in an article by R. M. Montgomery and J. W. Watkins, "High Data Rate Holographic Recording Using Acousto-Optic Input Devices", Proc Electro-Optical System Design Conference, New York, September 1972, Pages 295-308. The two-dimensional data transducer described in this article comprises a glass block which is provided with a plurality of piezoelectric transducers on one side thereof. Each of the transducers receives in a serial fashion a keyed high frequency signal which represents the item of data to be stored in the row of data block. The piezo transducer transmits a high frequency ultrasonic wave into the glass block which wave is modulated in the timing of the row of data and passes through the block at a speed of sound. As soon as the entire item of data fills the aperture of the glass block, the block is illuminated with an extremely short laser pulse during which time of illumination, the sound wave practically remains immoble. The spatially modulated light waves, which are a first order of diffraction, is focused by lenses onto a part of the storage tape to have the data recorded thereon.
Because of the requirement for a nano-second pulse laser with a high repetition frequency, which is greater than 1 kHz, the transducer described in the article is less suitable for certain applications. For example, this data transducer for reasons of efficiency is not suited for use in holographic block storage with the block sizes of about 10.sup.4 bits which are recorded on a stationary data carrier or medium.